1. Field of the Invention
The present invention relates to a motor-generator, which is comprised of a rotor of permanent-magnet pieces supported for rotation in a stator housing, a stator surrounding around an outside periphery of the rotor, and magnet coils arranged at axially opposing ends of the stator, each to each end, to keep a voltage steady.
2. Description of the Prior Art
Modern advanced permanent magnets of high performance have become much employed on a rotor of a motor-generator. Moreover, as the motor-generator having the rotor structure of permanent magnets is high in efficiency of electromechanical energy conversion and simple in construction, its use has recently grown in industrial machines and instruments of various kinds. Then, much research and development have continued to make the motor-generator compact or slim in construction, with even high performance and high power output, and correspondingly necessitated a diversity of parts and components.
In order to increase a torque at low speed in operation of the conventional motor-generator, it is effective to increase the strength of the magnetic field of the stator around the rotor, thereby raising the torque. With the motors, thus, increasing well the torque causes the increase of electromotive force at a low speed, contributing to the provision of commercially viable power source for machines. Among the rotating machinery employing the permanent-magnet rotor is, for example a permanent-magnet rotating machine disclosed in Japanese Patent Laid-Open No. 272850/1987. The prior permanent-magnet rotating machine has a rotor in which permanent magnets are arranged and containers are provided to contain therein magnetic material that is allowed to flow radially owing to the revolution of the rotor to thereby form magnetic pole pieces.
Moreover, another prior art of an a-c motor-generator capable of developing a high-power output is disclosed in Japanese Patent Laid-Open No. 236260/1995, in which a magnetic flux density is controlled in proportion to the speed in revolutions per minute (rpm) of the rotor to adjust properly an amount of the generated amperes or voltages. A control ring is arranged between the rotor and the stator for rotation relatively of them and further a permeable member is provided in such a manner as to come in and out contact with the control ring.
Further disclosed in Japanese Patent Laid-Open No. 261996/2000, which is co-pending application of the present inventor, is a high-torque motor-generator in which the permeable member is made of amorphous alloys to allow the magnetic forces to pass effectively through the small spaces, thereby increasing the torque at low speed in rpm of the rotor. The prior motor-generator is comprised of permeable members arranged in juxtaposition around a rotor shaft with nonmagnetic members being each interposed between any two adjoining permeable pieces, a magnetic path core arranged surrounding the outside periphery of the permeable members, platy permanent-magnets arranged around the outside periphery of the magnetic path core, and nonmagnetic reinforcing member fixed on the outside periphery of the permanent-magnets.
In the meantime, as most automotive electric equipments are designed to require either 12V or 24V, the automotive alternators need to have the generation characteristic capable of feeding the electric power matching to the voltage recited just above. Nevertheless, the d-c power of either 12V or 24V is too low to operate other industrial machinery such as auxiliaries mounted on an automobile, in which much power is required for their operation, thus apt to be much subject to transmission loss in the associated wiring. Moreover, a major problem exists in which too thick in cross section of conductor is necessitated for windings and wirings. To cope with this, the alternator is needed producing not only the electric power of low voltage matching to the voltage required for the automotive electric equipments but also another electric power having high tension adapted to energize the auxiliaries, industrial appliances, and so on. The high tension of the generated electric power reduces the transmission loss in the wiring, rendering the conductor such as windings thin in cross section, thereby making the alternator itself compact or slim in construction.
With the permanent-magnet motor-generator, the permanent magnet is fixed in magnetic flux density and accordingly unchanged in magnetic force, either at low speed or high speed. Nevertheless, the voltage and correspondingly the output of the motor-generator rises in proportion to the increase of the rpm of the rotor. Thus, the motor-generator designed to produce the desired output voltage when the rotor is at low speed comes to yield too high voltages to control them properly. As opposed to the event stated just earlier, the way to raise the output voltage at a low speed needs to either make the permanent magnet large in size or increase the current and also increase the number of loops or turns in the winding to intensify the strength of the magnetic field at the stator side with the result of yielding great torque. However, the output voltages at the high speed also become too high to control them adequately. To increase the torque in the motor-generator, moreover, it is needed to make the conductor wound on the stator core heavy in cross section to carry large current, thereby intensifying the magnetic force in the stator.
It is a primary object of the present invention to overcome the problems stated earlier and to provide a motor-generator having a voltage stabilizer, in which windings laid in slots of a stator core are grouped into more than one winding set that are connected in series and/or parallel to continue producing a desired output voltage independently of the variations of the rotor speed in rpm, and further in which a cylindrical magnetic path extends axially of the rotor in opposition to electromagnet coils arranged at axially opposing ends of the rotor, each to each end, and conduction to the electromagnet coils is controlled in such a manner as to intensify magnetic force in permanent-magnet pieces when the output voltage is low while weaken the magnetic force when the output voltage is high, thereby always ensuring the desired output voltage.
Another object of the present invention is the provision of a motor-generator raised in torque at low speed, characterized in that the electromagnets are installed at axial opposing ends of a rotor mounted on a rotor shaft, each to each end, to lead magnetic forces created by the electromagnets to the rear of a permanent magnet through a permeable member, adding the magnetic forces to magnetic forces developed in the permanent magnet to thereby increase the torque at low speed, and in that the revolving direction of the magnetic force developed from the permanent magnet is made in a loop unlike the whirl direction of the magnetic fields created by the electromagnets to compensate for a small area in the electromagnet core where the magnetic flux is allowed to pass through there, thereby ensuring the magnetic flux density enough to control the magnetic force by either adding or subtracting the magnetic forces of the electromagnets to or from the magnetic force of the permanent magnet, and further in that permanent-magnet pierces are circumferentially arranged with nonmagnetic pieces being each interposed between any two adjoining permanent-magnet pieces, thereby forming a multipolar cylindrical permanent-magnet construction where unlike poles alternate circularly, and an electromagnet core superior in magnetic permeability is arranged inside the permanent-magnet construction, thus allowing the magnetic flux from the electromagnets to flow through there.
A further another object of the present invention is to provide a motor-generator in which electromagnets are arranged at axially opposing ends of a rotor around a rotor shaft, whereby magnetic forces created by the electromagnets are led through a permeable member to the rear of a permanent-magnet member then, followed by added to the magnetic force of the permanent magnet, thus increasing the torque at low speed, and the permanent-magnet member is composed of platy permanent-magnet pieces elongated axially of the rotor, the permanent-magnet pieces being circumferentially arranged with nonmagnetic pieces being each interposed between any two adjoining permanent-magnet pieces, thereby forming a multipolar cylindrical permanent-magnet construction where the poles alternate in polarity circularly around the rotor shaft, and an electromagnet core superior in magnetic permeability is arranged inside the permanent-magnet construction.
The present invention is concerned with a motor-generator with a voltage stabilizer, comprising a multipolar permanent-magnet rotor mounted on a rotor shaft supported for rotation in a stator housing, a stator fixed to the housing with arranged around the rotor, and electromagnet coils fixed to axially opposing ends of the housing, each to each end, in opposition to axially opposing ends of the rotor, wherein the rotor is composed of a cylindrical magnetic path arranged around the rotor shaft and extended axially to areas confronting the electromagnet coils, a permeable member surrounding around the cylindrical magnetic path, and a permanent-magnet member of more than one permanent-magnet piece extended axially and arranged circumferentially around an outside periphery of the permeable member with N- and S-poles on either piece alternating in polarity circularly around the rotor, and wherein the cylindrical magnetic path includes an N-pole annular portion arranged confronting any one of the electromagnet coils, N-pole electromagnet magnetic paths stemming from the N-pole annular portion in opposition to the N-poles of the permanent-magnet pieces, an S-pole annular portion arranged confronting another of the electromagnet coils, and S-pole electromagnet magnetic paths stemming from the S-pole annular portion in opposition to the S-poles of the permanent-magnet pieces, the N-pole and S-pole electromagnet magnetic paths alternating in polarity circularly around the permanent-magnet member with nonmagnetic pieces being each interposed between any two adjacent electromagnet magnetic paths.
In an aspect of the present invention, a motor-generator is disclosed in which around the outside periphery of the permanent-magnet member there is provided a first reinforcing member to keep the permanent-magnet member against falling off the rotor owing to a high centrifugal force, the reinforcing member being made of high tensile carbon fibers of a core material, which is impregnated with molten aluminum then, followed by solidification.
In another aspect of the present invention, there is disclosed a motor-generator in which both the N-pole and S-pole electromagnet magnetic paths are encircled with a second reinforcing member to be formed in an overall cylindrical configuration.
In another aspect of the present invention, there is disclosed in which a motor-generator is disclosed in which nonmagnetic members of a material tough to pass the magnetic force, such as aluminum, copper alloys, resinous material, austenite SUS, and so on are filled in between any tip of the N-pole electromagnet magnetic path and the S-pole cylindrical portion and also between any tip of the S-pole electromagnet magnetic path and the N-pole cylindrical portion, and a clearance between any adjacent N-pole and S-pole electromagnet magnetic paths is made larger in distance than a sum of an air gap between the rotor and the stator and a clearance between the magnetic permeable member and the rotor.
In another aspect of the present invention, a motor-generator is disclosed in which molten aluminum or resinous material of heat-resistant property is charged in any clearance between any two adjacent permanent-magnet pieces and also any clearance between any adjacent N-pole and S-pole electromagnet magnetic paths.
In another aspect of the present invention, a motor-generator is disclosed in which the stator is comprised of a stator core with stator teeth arranged spaced circumferentially apart from each other to separate any two adjacent stator slots, and windings wound on stator teeth with spanning some stator slots so as to be substantially equal out of phase, and wherein the windings are each grouped into more than one winding set shifted from each other to form three-phase wye-connections, which are allowed to be connected either in series or in parallel, so that a controller selectively changes over among output terminals led out of the connections every winding set, thus producing a desired output power in accordance with a rpm of the rotor.
In a further another aspect of the present invention, a motor-generator is disclosed in which the stator windings are grouped into low-voltage winding sets and high-voltage winding sets, and the controller regulates magnetic flux to produce two types of power, which are different in rated voltage. Moreover, the low-voltage winding sets and the high-voltage winding sets are connected in parallel to give a generation characteristic of low-voltage, large-current.
In another aspect of the present invention, a motor-generator is disclosed in which the controller serves connecting in series the output terminals led out of the connections in response to an event where the engine or rotor is low in rpm, and reducing the number of the connections made in series as the rpm raises, thereby to ensure the desired output voltage kept always constant irrespective of variation in the rpm.
In another aspect of the present invention, a motor-generator is disclosed, in which with the rotor being operated in a preselected rpm range, the controller in response to the event where the output terminals are connected to provide the output of low voltage, makes the electromagnet coils conductive in a direction to increase the N-pole magnetic force, whereas in response to another event where the output is high in voltage, makes the electromagnets conductive in a reverse direction to decrease the N-pole magnetic force, thereby providing the desired output voltage kept always constant. Moreover, the controller includes a rectifier where a produced power of the desired voltage is rectified to a d-c, and an inverter yielding an a-c of a desired frequency.
In a further another aspect of the present invention, a motor-generator is disclosed in which the controller makes the electromagnet coils conductive in a manner to reduce the magnetic force of the permanent-magnet member when the motor-generator is used as a motor.
With the motor-generator constructed as stated earlier, the desired constant voltage may be ensured irrespective of variations in rpm of the rotor. Thus, the produced voltage may be controlled properly without going too high even at high speed. Most automotive electric systems need, for example the power of about 0.5 KWxcx9c1 KW at the voltages of 12Vxcx9c28V, whereas the auxiliaries or industrial equipment mounted on the automobile need the power of about 2 KWxcx9c3 KW. If someone could get the voltages of 12Vxcx9c28V to cover the power of about 2 KWxcx9c3 KW for the auxiliaries, the current value would become too large, thus causing power loss with much heating. As opposed to the condition stated earlier, the auxiliaries or auxiliary equipment is allowed to operate on the high tension of about 100Vxcx9c200V, thus involved in no problem of power loss in the wiring. Accordingly, the winding adapted to produce the high tension supplied to the auxiliaries, for example is allowed to make slender or thin the conductor in cross section, thereby contributing to rendering the generator slim in construction and light in weight. Besides, when any relay is used, the voltage may be more increased with the result of less current, thus protecting any contact against possible fusion.
With the motor-generator according to the present invention, simply connecting in series and/or in parallel the terminals of the windings in the winding sets is sufficient to produce the desired voltage, either at high speed or at low speed, thus, helping ensure always the proper voltage control.
According to the present motor-generator in which the electromagnet coils are arranged at the axially opposing ends of the stator, each to each end, while the permeable member extends outside the axially opposing ends of the rotor to areas confronting the electromagnet coils, when the rotor operates in the preselected rpm range, the controller in response to the event where the output terminals are connected to provide the output of low voltage, makes the electromagnet coils conductive in a direction to increase the N-pole magnetic force, whereas in response to another event where the output is high in voltage, makes the electromagnets conductive in a reverse direction to decrease the N-pole magnetic force, thereby providing the desired output voltage kept always constant.
The present invention is moreover concerned with a motor-generator in which the rotor is composed of an electromagnet core of permeable pieces extended axially to electromagnets and arranged circumferentially around the rotor shaft with nonmagnetic pieces being each interposed between any two adjacent permeable pieces, a cylindrical yoke of permeable material arranged over the electromagnet core, and a permanent-magnet member of more than one permanent-magnet piece arranged around an outside periphery of the cylindrical yoke, with nonmagnetic pieces being each interposed between any two adjacent permanent-magnet pieces, in the form of cylinder in such an array that the poles on either permanent-magnet piece alternate in polarity circularly around the rotor, and wherein the electromagnets are each composed of any one of axially opposing ends of the electromagnet core surrounding the rotor shaft, and an electromagnet coil arranged on a magnetic path case in the housing in opposition to the associated end, the electromagnet core being notches at angular intervals so as to provide magnetic circuits spaced circumferentially to flow the magnetic flux in axially but alternately opposite directions.
With the motor-generator constructed as stated just above, a current in the electromagnet coils laid on the inside surface of the magnetic path cases in the form of annular configuration induces a magnetic force in the cylindrical electromagnet core arranged over the rotor shaft, as the result of which the magnetic force created by the electromagnets is superposed on the magnetic force of the permanent magnets, thereby increasing the torque at low speed. In contrast, when the rotor is driven at high speed, a reverse current in the electromagnet coils generates a counter emf in the electromagnets to reduce the magnetic force developed by the permanent-magnets, thus erasing the excessive magnetic force to keep the torque proper at high speed. Moreover, the notches in the electromagnet core are to separate securely the lines of magnetic force apart from each other to keep the magnetic flux against leakage, thus helping ensure the path of the magnetic force from the electromagnets to the associated permanent-magnet piece in the permanent-magnet member. Thus, the controller, provided that it is set to make the electromagnet coils of the electromagnets conductive in the event of low speed, serves increasing the torque on the rotor shaft at low speed, whereas at high speed, makes the electromagnet coils conductive in reverse direction to the event of low speed, reducing the high emf at high speed.
With the motor-generator in which the controller energizes the electromagnet coils of the electromagnets in response to the event where the rpm of the rotor is small to increase the magnetic flux created by the electromagnets, it will be possible to develop a torque several times as big as the conventional rotors, thereby increasing the torque at low speed, which has been the major problem faced in the permanent-magnet motor-generator. For example, supposing the permanent magnet has the magnetic flux density of about 1.5 T, the flux density input to the stator side could reach about 2.3 T by virtue of the additional magnetic force created by the electromagnets.
In an aspect of the present invention, a motor-generator is disclosed in which the permeable pieces in the electromagnet core are each extended axially with a width equal to any one permanent-magnet piece of the permanent-magnet member so that the magnetic flux created by the electromagnets is allowed to enter the magnetic poles of the permanent-magnet member through the yoke and then flow to the stator side.
In another aspect of the present invention, a motor-generator is disclosed in which any permeable piece of the electromagnet core is arranged in opposition to the permanent-magnet piece having poles directed radially with the S-pole being outside periphery and the N-pole inside periphery, and any adjacent permeable piece is in opposition to the permanent-magnet piece with the S-pole being inside periphery and the N-pole outside periphery, thus, ensuring a flow of magnetic flux along the poles of the permanent-magnet member.
In another aspect of the present invention, a motor-generator is disclosed in which the magnetic flux passing through the rotor having the permanent-magnet pieces into the stator side flows along either a magnetic circuit coming from and entering any permanent-magnet piece through the yoke, any adjacent permanent-magnet piece, any stator tooth, a stator core and another stator tooth or other magnetic circuit opposite in direction at the permanent-magnet piece having reversed poles, and the yoke has a radial thickness that might be substantially saturated with the magnetic flux of the permanent-magnet member.
In another aspect of the present invention, a motor-generator is disclosed in which the magnetic flux created by the electromagnet passes either a closed path coming from and entering the electromagnet core through the yoke, the stator tooth, the stator core, the magnetic path case and the electromagnet coil or other magnetic path in opposite direction.
In another aspect of the present invention, a motor-generator is disclosed in which the electromagnet core is made of any material much high in magnetic permeability such as ferrite, molybdenum-nickel-iron alloy, sendust, amorphous ferroalloys, and so on.
In a further another aspect of the present invention, a motor-generator is disclosed in which a controller in response to a low speed in rpm of the rotor shaft makes the electromagnet coils conductive to superpose additional lines of magnetic force flowing through the electromagnet core on the magnetic force created by the permanent-magnet member, thereby increasing a torque at low speed of the rotor shaft.
In another aspect of the present invention, a motor-generator is disclosed in which the controller in response to a high speed of the rotor shaft makes the electromagnet coils conductive reversely in direction to the event at low speed, thus developing an additional magnetic force acting oppositely in direction to the magnetic force of the permanent-magnet member so as to reduce the torque at high speed of the rotor shaft.
In another aspect of the present invention, a motor-generator is disclosed in which on readjustment of the motor, the controller makes the electromagnets conductive in a direction opposite to the event at low speed so as to render the magnetic force of the permanent-magnet member roughly null, thereby making the occurrence of cogging less.
Moreover, the present invention relates to a motor-generator wherein the rotor is composed of permeable member of permeable pieces arranged circumferentially around the rotor shaft in the form of cylinder with nonmagnetic pieces being each interposed between any two adjacent permeable pieces, a cylindrical magnetic path core of permeable pieces arranged circumferentially over the permeable member with nonmagnetic pieces being each interposed between any two adjacent permeable pieces, and a permanent-magnet member of more than one permanent-magnet piece arranged around an outside periphery of the magnetic path core, with nonmagnetic pieces being each interposed between any two adjacent permanent-magnet pieces, in the form of cylinder in such an array that the poles on either permanent-magnet piece alternate in polarity circularly around the rotor, and wherein there are provided electromagnet cores each composed of radial extensions coming in close contact with the permeable member of the rotor to ensure axial flows of magnetic flux, and an annular portion notched at angular intervals to separate axially the radial extensions apart from the rotor.
The motor-generator constructed as stated just above is intended to realize the high torque at low speed. The electromagnet coils laid on the inside surface of the magnetic path cases in the form of annular configuration are made conductive in accordance with the instruction from the controller to induce a magnetic force in the cylindrical electromagnet core arranged over the rotor shaft. The magnetic force created by the electromagnets is superposed on the magnetic force of the permanent magnets, thereby increasing the torque at low speed. In contrast, when the rotor is driven at high speed, a reverse current in the electromagnet coils generates a counter emf in the electromagnets to reduce the magnetic force developed by the permanent-magnets, thus erasing the excessive magnetic force to keep the torque proper at high speed.
With the motor-generator in which the controller makes the electromagnet coils of the electromagnets conductive in response to the event where the rpm of the rotor is small to increase the magnetic flux created by the electromagnets, a torque several times as big as the conventional rotor alone is developed to increase the torque at low speed, which has been the major problem faced in the permanent-magnet motor-generator.
In an aspect of the present invention, a motor-generator is disclosed in which the permeable member is formed in a cylindrical configuration where platy laminations, each equal in width with any permanent-magnet piece of the permanent-magnet member, are arranged circumferentially with any nonmagnetic member being interposed between any two adjacent platy laminations to help ensure the flow of magnetic flux along the poles of the permanent-magnet member.
In another aspect of the present invention a motor-generator is disclosed in which any one electromagnet core at any one axial end of the rotor is arranged in opposition to any permanent-magnet piece, which is disposed with the N-pole being outside the curved periphery and the S-pole inside the curved periphery, whereas another electromagnet core at axially opposing end of the rotor is arranged in opposition to any permanent-magnet piece, which is disposed with the N-pole being inside the curved periphery and the S-pole outside the curved periphery, thereby helping ensure the flow of magnetic flux along the poles of the permanent-magnet member.
In another aspect of the present invention, a motor-generator is disclosed in which the radial extensions of the electromagnet core make close contact with their associated axial ends of the permeable member, the magnetic path core and the permanent-magnet member.
In a further another aspect of the present invention, a motor-generator is disclosed in which both the permeable member and the electromagnet core are made of any material much high in magnetic permeability such as ferrite, molybdenum-nickel-iron alloy, sendust, and so on.
In another aspect of the present invention a motor-generator is disclosed in which a controller in response to a low speed in rpm of the rotor shaft makes the electromagnet coils conductive to superpose additional lines of magnetic force flowing through the electromagnet core on the magnetic force created by the permanent-magnet member, thereby increasing a torque at low speed of the rotor shaft.
In another aspect of the present invention, a motor-generator is disclosed in which the controller in response to a high speed of the rotor shaft makes the electromagnet coils conductive in opposite direction to the event at low speed, thus developing an additional magnetic force acting oppositely in direction to the magnetic force of the permanent-magnet member so as to reduce the torque at high speed of the rotor shaft.
In another aspect of the present invention, a motor-generator is disclosed in which the annular portion of the electromagnet core is made integral with the permeable member.
Other objects and features of the present invention will be more apparent to those skilled in the art on consideration of the accompanying drawings and following specification wherein are disclosed preferred embodiments of the present invention with understanding that such variations, modifications and elimination of parts may be made therein as fall within the scope of the appended claims without departing from the spirit of the invention.